Unit Price Comparison
Put four packs side by side and see the price per gram — the only comparison that is actually fair. The big one is cheaper surprisingly often, and not always.
Why the shelf label is not enough
Shops price packs so that comparing them in your head is hard. 500g for 45, one kilo for 82, two and a half kilos for 199 — the only way to know is to work out what one gram costs in each, which is exactly what nobody does while standing in an aisle.
Do it here and the answer is often not the one the packaging suggests. In the example above the middle pack wins, and the largest one is the worst buy of the three.
Bigger is cheaper — except when it is not
The family pack being better value is a habit of thought, not a law. Shops know about the habit and price accordingly, and the large size is frequently the one carrying the promotion's cost. Supermarkets in several countries are now required to print a unit price on the shelf edge precisely because of how often the intuition is wrong.
Then there is the part arithmetic cannot help with. A bigger pack is only cheaper if you use all of it. Two kilos of something that goes stale in a fortnight, bought by a household of two, is the most expensive option on the shelf no matter what the maths says.
Mixed units are refused, on purpose
Grams and kilos are compared happily, and so are millilitres and litres, because they are the same measure written differently. Weight against volume is not, and neither is either of them against a count of pieces.
A tool that quietly compared 500g with 500ml would produce a confident number that means nothing, so this one stops and says so. If you are comparing a liquid sold by weight in one pack and by volume in another, you need its density, and that is a different question.
The number to remember
Not the winner — the gap. Twelve per cent on a weekly shop is real money over a year; two per cent is inside the noise of where you happen to shop that week and not worth walking to another aisle for.
Frequently asked questions
Can I compare grams with millilitres?
No, and no tool honestly can. Weight and volume are different measures, and converting between them needs to know how dense the thing is. The page refuses rather than producing a confident number that means nothing.
Why is the biggest pack not the cheapest?
Because shops price to the habit of assuming it is. The large size often carries the cost of whatever promotion is running on the small one. Several countries now require a unit price on the shelf label for exactly this reason.
Does it handle a buy-one-get-one offer?
Not directly, but you can do it yourself: enter the price you pay and the total size you go home with. Two packs of 500g for the price of one is 1000g at that price.
What if the price is per piece?
Choose 'pieces' for the size unit and the comparison is per item. All the packs being compared have to use pieces - a count cannot be weighed against a weight.
Should I always buy the best value?
Only if you will use it. A bigger pack is cheaper per gram and more expensive overall if half of it is thrown away, and the arithmetic here cannot see your kitchen.
Is my text sent anywhere?
No. Everything happens in JavaScript inside your own browser. Nothing is uploaded and nothing is saved - close the tab and it is gone.